Optimum raidz configuration for my system

[Phak1]

I am new to freenas. I previously had a HP mediaSmart home server for several years. Not a good experience to say the least. After it crashed for the third time (2 PS then a MB failure) I decided to build my own NAS server. Not knowing how freenas works, I took my two 1TB WD black drives removed from my crashed HP mediaSmart served and I bought a new 2TB WD red drive to add to the server loaded freenas 9.2.1.5 and discovered that I could only mirror the two 1TB drives and stripe the 2TB drive. I was going to use a raidz1 and upgrade the 1TB TO 2 as money allowed. Now after reading the forums, I need to rethink my strategy.

Can I start freenas vpool with the existing drives I have then transfer the data to a new vpool as money allows?

Should I buy another 2TB drive, install the drives in a raidz2 configuration using freenas 8.2.3 then upgrade to 9.2.1.5? I could the upgrade the 1TB drives later when funds become available.

I don't have the funds to buy sufficient identical drives to have an ideal raidz2 configuration.

Any foresight would be appreciated.

My new system:
Lian Li case PC-
GIGABYTE|GA-H97N-WIFI H97 ITX
ANTEC PS EA-380D GREEN RT
CPU INTEL|CELERON G1840 2.8G 2M R
USB Sandisk 8GB SDCZ33-008G-A46 R
MEM 4Gx2|G.SKILL F3-12800CL9D-8GBXL
WD 2TB Red drive WD20EFRX 64M

 

[danb35]

I'm not sure where your question about using 8.2.3 is coming from--I don't see any reason to do that. Yes, you can set up a RAIDZ with dissimilar drives, but the capacity will be defined by the smallest drive. Thus, a RAIDZ1 with 2 x 1 TB drives and 1 x 2 TB drive will have ~ 2 TB of net capacity. A RAIDZ2 with 2 x 1 TB drives and 2 x 2 TB drives will have the same ~ 2 TB net capacity. When you replace the 1 TB drives with 2 TB or larger drives, your net capacity will grow to ~ 4 TB. Please note that you CANNOT add a drive to a RAIDZ group--once you create it, it will always consist of the same number of drives. You can replace the drives with larger ones, but you can't add drives to it.

With respect to your other hardware choices--neither the motherboard nor the RAM you've chosen support ECC, which is strongly recommended for data integrity when using ZFS. The TYAN S5533GM2NR-LE (http://www.newegg.com/Product/Product.aspx?Item=N82E16813151295) does, is the same form factor, does away with useless (for this application) features like audio and WiFi, and adds IPMI, which lets you run the server completely headless. I haven't used it, but the review on NewEgg seems happy with that board for FreeNAS.

For RAM, I'd suggest a single 8 GB stick rather than 2x 4 GB. Yes, you'll lose the performance boost of dual-channel RAM, but you'll have a free memory slot, so upgrading will just be a matter of adding a new stick rather than throwing out the existing RAM.

 

[Phak1]

First I want to thank you for you're quick response. It's nice to know that freenas has such a support group.

I purchased the MB and ram prior to knowing the optimum hardware configuration for freenas. I've built computers for home use for years and was going on my past experiences. My mistake for not fully investigating freenas.

As for using 8.2.3, I tried creating a vpool using the three drives and did not have that option to use raidz2, only mirror the two 1TB, stripe the 2TB or stripe them all. Past forum posts say to create the vpool with Ver. 8.2.3 then upgrade to 9.2.1.5.

I don't think I understand the term "headless server" when it comes to freenas. The HP mediaSmart server was considered headless (no video out or keyboard/mouse ports in) and it was a nightmare when something went wrong. Replace parts until it worked again.

So the bottom line is I would like to run the three drives as raidz2. How do I do that in 9.2.1.5?

 

[danb35]

It isn't possible to configure three disks as RAIDZ2--you need at least four for that. With four mismatched drives, you may need to use the "manual" ZFS configuration, but you would be able to create a RAIDZ2 pool under 9.2.1.5.

My servers are tucked away in a closet with no keyboard or monitor. Since they're Unix-based, I can use ssh for most admin tasks, but sometimes I need direct console access. IPMI lets me do that over the network, just like having a keyboard and monitor directly attached. Very convenient, IMO.

 

[Phak1]

Guess I'm going to buy another drive prior to proceeding.

I'll read up on manual ZFS Configuring.

I have one last question. Can I have multiple vpools in freenas? I'm thinking of future expansion.

 

[danb35]

Yes, you can have multiple zpools. You can also expand a zpool by adding a new vdev. So, if you set up your system with four disks in a RAIDZ2 configuration now, you can later buy four more disks and add them as a second RAIDZ2 to your existing zpool.

You may want to consider a different storage layout: striped mirrors. If you buy a second 2 TB disk, you could mirror the 2x 1 TB disks, mirror the 2x 2 TB disks, and stripe the mirrors, which would give you a net capacity of 3 TB. This would be faster than RAIDZ2, and have greater capacity. However, there would be a slight loss in redundancy. With a RAIDZ2, you could lose any two drives with no harm to your data. With striped mirrors, you can lose one drive from each mirror without harm, but if you lose both drives in any mirror, all your data is lost. Thus, the striped mirrors could tolerate the loss of two disks as well, as long as they were the "right" two disks.

 

[Phak1]

Using that logic (mirroring) could I start my freenas using the two 1TB DRIVES in one vdev than add the two 2TB DRIVES (when I get the second) as another vdev in the same vpool. Would the results be the same?

 

[Phak1]

Also, can I copy the data from one vpool to another?

 

[danb35]

Yes, you can copy data from one zpool to another. They appear as separate volumes, so you can use any of the standard Unix tools (cp, rsync, etc.). You can share them and copy data on your network clients. Or you can use zfs replication, which is probably the best option to make an exact copy.

On your mirroring question, yes, you can do exactly as you describe: mirror the 1 TB drives today, add a mirror of 2 TB drives when you get a second one, and add a third mirror of 3 TB drives in the future when you buy a pair of them. You will, of course, sacrifice half of your total capacity to the mirrors. Be sure to read cyberjock's powerpoint explaining some of the ZFS basics--it's in the first sticky thread in this forum.

 

[Phak1]

Thanks for you advice. I can now move forward on my project armed with the knowledge that I am not locked into the present configuration.